1. Field of the Invention
The present invention relates to a method of manufacturing a roller stamp and, more specifically, to a method of forming a stamp pattern on a stamp roller without using a stamp die after the stamp roller is mounted to a stamp case.
2. Description of the Related Art
Japanese Unexamined Patent Publication No. 3-96383 discloses six conventional methods of forming a stamp pattern on a flat stamp whose stamp surface is made of a porous sponge rubber capable of being impregnated with ink. According to those methods, a stamp pattern is formed on the stamp surface by selectively closing the pores in the stamp surface: (1) applying an adhesive on the stamp surface in accordance with the stamp pattern by means of a screen-printing method; (2) masking the stamp surface in accordance with the stamp pattern, spraying an adhesive on the surface and removing the mask; (3) forming a thermosensitive film on the stamp surface and removing the film in accordance with the stamp pattern by means of a thermal head or heat flashes; (4) applying a thermal transfer film in accordance with the stamp pattern by means of a thermal head or headlashes; (5) heating and melting the stamp surface in accordance with the stamp pattern by means of a thermal head or (6) applying a light-curing resin on the surface and exposing the resin to light in accordance with the stamp pattern.
Japanese Unexamined Patent Publication No. 6-155698 discloses a method of forming a stamp pattern on a flat stamp whose stamp surface is made of a formed polyolefin sheet. According to this method, a stamp pattern is formed on the sheet by heating it in accordance with the pattern.
Further, Japanese Unexamined Patent Publication No. 7-251558 discloses another method of forming a stamp pattern on a flat stamp whose stamp surface is made of an elastic resin sheet. According to this method, a stamp pattern is formed on the sheet by pressing it between a platen and a thermal head. The foamed polyethylene developed by Yamahachi Chemical Co. Ltd. has been found an excellent material for a stamp sheet with which the above methods work very well in manufacturing stamps of the type impregnated with ink. Under all of the methods discussed above, however, a stamp pattern is formed on a foamed thermoplastic resin sheet before the sheet is attached to a flat stamp.
In addition to a flat stamp, there is available a roller stamp capable of continuously carrying out stamping. In manufacturing conventional roller stamps, a stamp pattern is formed by rolling a stamp material on a heated engraved molding die or by forming a pattern on a formed sheet, using the conventional methods discussed above, and winding the sheet around the stamp roller.
As mentioned above, the conventional methods of manufacturing a flat stamp all use a flat sheet, form a stamp pattern on the sheet and then attach the sheet to the flat stamp surface. Thus, according to the conventional methods, a stamp pattern cannot be formed after the flat sheet is attached to the stamp surface. Moreover, a flat stamp requires a large pressing force for stamping. It is difficult to apply a pressing force uniformly to the entire stamp surface of a flat stamp. Thus, an irregular stamp impression is often inescapable.
Generally, a roller stamp does not require a large pressing force upon stamping. An irregular stamp impression rarely occurs with a roller stamp. However, with respect to the roller stamp which requires an engraved molding die to form a stamp pattern, its manufacturing process inevitably includes an additional step of preparing an engraved molding die. Since an engraved molding die determines a stamp mark, an infinite variety of dies would have to be prepared in advance to meet unknown needs of customers, and the stamp pattern cannot be changed at the customer's request.
With respect to the roller stamp in which a stamp pattern is formed on a sheet that is then wound around a roller, its production is cumbersome in that a stamp pattern must be formed on the sheet before it is wound around the stamp roller. Therefore, like the flat stamp discussed above, an infinite variety of stamp sheets would have to be prepared in advance to meet unknown needs of customers, and the stamp pattern cannot be changed at the customer's request.